001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 * 
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 * 
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.log4j.helpers;
019
020import java.util.Enumeration;
021import java.util.NoSuchElementException;
022
023/**
024   
025  An always-empty Enumerator.
026
027  @author Anders Kristensen
028  @since version 1.0
029 */
030public class NullEnumeration implements Enumeration {
031  private static final NullEnumeration instance = new NullEnumeration();
032  
033  private
034  NullEnumeration() {
035  }
036  
037  public static NullEnumeration getInstance() {
038    return instance;
039  }
040  
041  public
042  boolean hasMoreElements() {
043    return false;
044  }
045  
046  public
047  Object nextElement() {
048    throw new NoSuchElementException();
049  }
050}